Bumblebees moving up: shifts in elevation ranges in the Pyrenees over 115 years

In a warming climate, species are expected to shift their geographical ranges to higher elevations and latitudes, and if interacting species shift at different rates, networks may be disrupted. To quantify the effects of ongoing climate change, repeating historical biodiversity surveys is necessary. In this study, we compare the distribution of a plant–pollinator community between two surveys 115 years apart (1889 and 2005–06), reporting distribution patterns and changes observed for bumblebee species and bumblebee-visited plants in the Gavarnie-Gèdre commune in the Pyrenees, located in southwest Europe at the French–Spanish border. The region has warmed significantly over this period, alongside shifts in agricultural land use and forest. The composition of the bumblebee community shows relative stability, but we observed clear shifts to higher elevations for bumblebees (averaging 129 m) and plants (229 m) and provide preliminary evidence that some bumblebee species shift with the plants they visit. We also observe that some species have been able to occupy the same climate range in both periods by shifting elevation range. The results suggest the need for long-term monitoring to determine the role and impact of the different drivers of global change, especially in montane habitats where the impacts of climate changes are anticipated to be more extreme.

Feeding habits of the cockfish, Callorhinchus callorynchus (Holocephali: Callorhinchidae) from off northern Argentina

ABSTRACT The feeding habits of Callorhinchus callorynchus were investigated in coastal waters off northern Argentina. The effect of body size, seasons and regions was evaluated on female diet composition using a multiple-hypothesis modelling approach. Callorhinchus callorynchus fed mainly on bivalves (55.61% PSIRI), followed by brachyuran crabs (10.62% PSIRI) and isopods (10.13% PSIRI). Callorhinchus callorynchus females showed changes in the diet composition with increasing body size and also between seasons and regions. Further, this species is able to consume larger bivalves as it grows. Trophic level was 3.15, characterizing it as a secondary consumer. We conclude that C. callorynchus showed a behavior of crushing hard prey, mainly on bivalves, brachyuran, gastropods and anomuran crabs. Females of this species shift their diet with increasing body size and in response to seasonal and regional changes in prey abundance or distribution.

Species interactions and contemporary evolution

All organisms live within a diverse assemblage of many other species. Even with strict boundaries to gene flow, species interact in ways that shape their evolutionary dynamics. This chapter outlines how species interactions affect evolution of constituent species within a community. Models of competitive communities illustrate how interactions can constrain evolution, as species shift to occupy new regions with conditions similar to those they were previously adapted to. In contrast, coevolutionary interactions can stimulate evolution and amplify responses to environmental change. Experimental evolution on bacteria isolated from tree-holes formed by the roots of beech trees shows how species adapt to the presence of other species, leading to a decline in the strength of competition. Much more work is needed to investigate these effects in model assemblages of interacting species.

Parallel functional and stoichiometric trait shifts in South-American and African forest communities with elevation

Elevational gradients are an empirical tool to assess long-term forest responses to environmental change. We studied whether functional composition of tropical forest along elevational gradients in South America and in Africa showed similar shifts. We assessed community-weighted functional canopy traits and indicative δ15N shifts along two new altitudinal transects in the tropical forest biome of both South-America and Africa. We found that the functional forest composition response along both transects was parallel, with a species shift towards more nitrogen conservative species at higher elevations. Moreover, canopy and topsoil δ15N signals decreased with increasing altitude, suggesting a more conservative N cycle at higher elevations. This cross-continental study provides two empirical indications that both South-American and African tropical forest show a parallel response along altitude, driven by nitrogen availability along the altitudinal gradients, inducing a parallel shift in the functional forest composition. This highlights the importance of nutrient availability for tropical forest in a changing world. More standardized research, and more research on other elevational gradients is needed to confirm our observations.